In Situ Helium Isotope Microimaging of Meteorites

Area of Science:

• Cosmochemistry
• Planetary Science
• Geochemistry

Background:

• Isotope imaging is vital for tracing elements in extraterrestrial materials.
• Noble gas analysis in meteorites reveals early solar system processes and trapped solar wind.
• Previous methods lacked the resolution to identify solar wind gas carriers.

Purpose of the Study:

• To develop a high-resolution imaging technique for in situ noble gas analysis.
• To identify the microscale carriers of solar wind helium in meteorites.

Main Methods:

• Developed 4He isotope imaging using secondary neutral mass spectrometry with strong field postionization.
• Achieved 2 micrometer lateral resolution and a 4He detection limit of 2 x 10^17 cm^-3.
• Applied the technique to the Northwest Africa 801 carbonaceous chondrite.

Main Results:

• Successfully imaged solar wind 4He distribution at micrometer resolution.
• Identified fine-grained particles as the primary carriers of solar wind 4He.
• Observed that these carriers are sparsely distributed within the meteorite matrix.

Conclusions:

• The new technique enables unprecedented micrometer-scale analysis of noble gases in meteorites.
• Solar wind 4He in carbonaceous chondrites is predominantly hosted in small, scattered mineral grains.
• This advancement opens new avenues for studying early solar system evolution and gas trapping mechanisms.